An analysis of posynomial MOSFET models using genetic algorithms and visualization
Name
220925381-MIT.pdf
Description
Full printable version
Size
3 MB
Format
Adobe PDF
Checksum (MD5)
37f7697dc4ec01552b176e9cb1abd2f5
Author(s)
Salameh, Lynne Rafik
Advisor(s)
Una-May O'Reilly.
Alternative Title
Genetic algorithms as CAD tools for analog design
Date Issued
2007
Publisher
Massachusetts Institute of Technology
Abstract
Analog designers are interested in optimization tools which automate the process of circuit sizing. Geometric programming, which uses posynomial models of MOSFET parameters, represents one such tool. Genetic algorithms have been used to evolve posynomial models for geometric programs, with a reasonable mean error when modeling MOSFET parameters. By visualizing MOSFET data using two dimensional plots, this thesis investigates the behavior of various MOSFET small and large signal parameters and consequently proposes a lower bound on the maximum error, which a posynomial cannot improve upon. It then investigates various error metrics which can be used to balance the mean and maximum errors generated by posynomial MOSFET models. Finally, the thesis uses empirical data to verify the existence of the lower bound, and compares the maximum error from various parameters modeled by the genetic algorithm and by monomial fitting. It concludes that posynomial MOSFET models suffer from inherent inaccuracies. Additionally, although genetic algorithms improve on the maximum model error, the improvement, in general, does not vastly surpass results obtained through monomial fitting, which is a less computationally intensive method. Genetic algorithms are hence best used when modeling partially convex MOSFET parameters, such as ro.
Description
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 89-90).
Subjects
Electrical Engineering and Computer Science.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
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